Laesio enormis (Latin: abnormal harm) is a legal doctrine that gives a contracting party the ability to rescind an agreement if the price of exchange is less than a certain proportion (for instance one half, or two thirds) of its actual value.
The principle was developed as a way to ensure that people received a just price (iustum pretium) in exchange, and in opposition to the Imperial Roman view, found in the Corpus Juris Civilis,[1] that the parties to an exchange were entitled to try to outwit one another.
[6] The Louisiana Civil Code article 2589 permits rescission for lesion beyond moiety.
It states that the seller may rescind the sale of an immovable when the price, or the property it is exchanged for, is less than one half of the fair market value.
This form of laesio enormis has been criticized from a legal and economics perspective for its inefficient incentives.